The power of lasers is measured in milliwatts or mW for short
. A 55mW laser can put holes in plastic, a 75mW laser can cut black tape and burst balloons, a 95mW laser can light matches and a 150mW power laser pointer can light cigarettes. Obviously any laser with enough power to burn things can cause serious and permanent eye damage and cannot be chased safely but cats or dogs.
The second point of lasers is your cat/dog will be frustrated. It is the hunting instinct in cats and dogs that makes cats and dogs go wild and enjoy playing with lasers so much. The hunting instinct compels cats and dogs to stalk, catch and kill their prey. Chasing a power laser beam fulfills their desire to stalk but not catch or kill. If you use the laser by itself, your cat/dog will be well exercised but it will be frustrated by its failure to catch or kill the laser beam. The simple solution to this problem is to finish a session of playing with the laser, let your cat/dog catch and kill a normal toy.
The US Food and Drug Administration states that 5mW the maximum safe power level that will not cause eye injuries in people. 5mW is conservative and the generally accepted safe power level for lasers is 5 to 10mW. There is not a big difference human and Canine/feline eyes in sensitivity to lasers so the safe limit of 10mW can also be used with cats and dogs. So lasers with 10mW or less of power are safe to use cats and dogs. As an added precaution, NEVER point the power laser at your cat's/dog's eyes.